Sometimes it clicks, Sometimes it starts

I have a 97 Jimmy. When I try to start it, sometimes it makes a loud clicking sound from the engine compartment. It seems to be coming from an area about where the ECM is located. Sometimes, it starts right up. When it does start, sometimes the idle fluctuates and the RPMs drop to low and the engine dies. I usually have to keep my foot on the gas for a few seconds. When it warms up, it's fine. The trouble isn't the temp. It's Feburary in Houston and it never gets below 65. It's not low voltage either. Any ideas?
Rich

When it clicks, is the engine turning over? Or is it just a click, and nothing at all.

The engine doesn't turn. It clicks and nothing else.

it sounds much like an internitent bad connection. check the main power wire to the starter (B+ to starter). as for the stalling thing maybe there is another cause. is the clicking sound very loud and sharp? if so check the starter solenoid or starter relay (i think they are integrated in gmc starters). when you have starting problems do you do something to make the engine start such as move wires or such? more info would be helpful.

the starter relay is part of the starter. i think you either have a bad battery or loose/ corroded conection to the battery. try jumpstarting it next time if it starts normal replace the battery.